Comprehensive set including Chrome Molybdenum screw and bolt extractors and Vanadium stud extractors. Screw-type has left-hand threads for removing recessed bolts/studs. Bolt type features reverse spiral flutes which bite down on rounded off bolts. Stud type includes three internal rollers clamping down and gripping stud allowing removal/installation. Suitable for professional workshop. Supplied in storage case.18pc Bolt Stud & Screw Extractor Set• Comprehensive set including Chrome Molybdenum screw and bolt extractors and Vanadium stud extractors.• Screw-type has left-hand threads for removing recessed bolts/studs.• Bolt type features reverse spiral flutes which bite down on rounded off bolts.• Stud type includes three internal rollers clamping down and gripping stud allowing removal/installation.• Contents: 3/8Sq Drive Bolt Extractor Set; 10 11 12 13 14 15 16 17 19mm Screw Extractor Set; M14-M18 M11-M14 M8-M11 M6-M8 M3-M6 1/2Sq Drive Stud Extractor Set; 6 8 10 12mm.• Suitable for professional workshop.• Supplied in storage case.• Lifetime Guarantee*.• Model No. AK751Model No: AK751:Brand: Premier:Contents: 3/8Sq Drive Bolt Extractor Set; 10PTDSEAAK751